ardinal Bernard F. Law of Boston resigned unexpectedly yesterday as chairman of the board of trustees of the Catholic University of America, a position he has held for 12 years, university officials said.

Law's term as chairman of the trustees at the school in Washington, D.C., was not scheduled to end until June. This fall, he had said he would not seek another term as chairman.

The Rev. David M. O'Connell, Catholic University's president, said he was somewhat surprised, but not shocked, because of the intense pressure Law has been under because of the sexual abuse scandle in the Boston archdiocese.

''I wasn't bowled over,'' said O'Connell, who said Law called him last week to say he would be quitting. O'Connell said he did not ask Law why he was leaving early or whether he planned to resign as cardinal, as well.

''My own thought was that with each passing day, as more information was released [in Boston], he seemed more and more drawn in the direction of resigning'' at the university, O'Connell said. ''He has an awful lot to do in Boston.''

O'Connell acknowledged that Law's resignation, disclosed while the cardinal was making a surprise visit to the Vatican to discuss issues regarding the sexual abuse crisis, might fuel speculation he plans to step down as archbishop.

But O'Connell said Law's immediate resignation from the university post was driven more by the fact the board was meeting this week. As a cardinal, he will remain a member of the 50-member board of trustees, along with seven other US archbishops.

Law's position at Catholic University has stirred some controversy among students. In March, an open forum was held to discuss the crisis in the church, with most questions focused on Law and how he could serve on the board, in light of the scandal.

''My 12 years of service as chairman of the board have been an extraordinary, positive experience for me,'' Law said in his resignation letter. ''I leave this position grateful for the opportunity I have had to work with so many wonderfully dedicated people who demonstrate their support for and commitment to the Catholic University of America in so many wonderful ways.''